1. Field of the Invention
This invention relates generally to optical image processing systems and more particularly to a system which will permit the detection, recognition and location of wire type obstacles or targets.
2. Description of the Prior Art
Over a relatively short period of time the helicopter has become an integral part of military hardware. The unique capabilities and characteristics of this type of aircraft has provided solutions to tactical and logistic situations heretofore not easily overcome; however, new problems are simultaneously introduced. Helicopters inherently operate at speeds which make them vulnerable to ground based fire. This low speed operation in conjunction with their characteristic sound levels and patterns makes location and destruction a relatively easy task for an enemy with only modest technological sophistication. Accordingly, helicopter survival in a moderate threat environment is intimately dependent upon operating at low flight levels, commonly referred to as nap of the earth (NOE). Maximum survival and mission requirements for a helicopter dictate that NOE operation be carried on at night, preferably in the absence of moonlight, and under weather conditions far from ideal.
The NOE mode of operation, however, introduces flight hazards such as trees, buildings, poles, wires and even local variations of terrain. The problems are further compounded by secondary sensor effects which could be compensated when the operational environment is more nearly "normal". For example, with conventional radar, side lobe and multipath effects are compensated by time and/or amplitude discrimination. However in an NOE operation, the secondary effects become equal in magnitude to the signal sought and the system accordingly fails in its intended task.
The single most irksome impediment for NOE operations day or night, however, is the detection of wires and/or wire-like objects. This detection and recognition must occur at a range sufficiently great to permit the pilot to accomplish an evasive maneuver, while at the same time providing as little distraction as possible, taking into account the aircraft flight parameters and pilot reaction time. The uniqueness of a wire as distinguished from other categories of obstacles or radar targets has resulted in a solution as provided by the subject invention which utilizes charge coupled device (CCD) technology such as disclosed in a publication entitled, "Low Light Level Performance of CCD Image Sensors", by David D. Wen, which appeared in the proceedings of the 1975 International Conference on CCD Applications, San Diego, California, October, 1975, at pages 109-119, inclusive and U.S. Pat. Nos. 3,806,772 and 3,999,082 issued to J. Early. Additionally, infra-red (IR) detector arrays using charge coupled devices are disclosed for example in U.S. Pat. Nos. 3,902,066, Roosild, et al., 3,883,437, Nummedal, et al., and 3,808,435, Bate, et al.